Move update settings out of the main activity

The settings activity still contains only few lines of code. Until now I
was forced to check whether the settings are all set twice: in onCreate
and onResume. Everytime onCreate is invoked, onResume will be invoked as
well.

Hence, I have moved the code out and override the onPause method of the
settings activity. This way the settings are only updated after the user
went on the settings activity.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Remove save instance state keys from resource file

In retrospective it seems ridiculous to write the string key for storing
activity state values in the resource XML file. I have removed them and
hard-coded the values into the source code. This way the code becomes
shorter and to my mind more clear.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Unlock interface after exception occurred

Just added an unlock interface call to the processing of problem
alerting in the main activity so the interface does not get stuck
in an infinite progress bar loop.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Complete main activity refactoring more or less

I do not know whether I will overhaul the main activity code again in
the near future, but for now I have made all the changes I had in mind.
Especially removing all the calls directly to the controller's inbox
handler, which is now all done via the ClientController class.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Purge further code

As expected I have removed the method which checks whether the network
is currently available, for instance it might not be available due to
activated airplane mode. I did not find a suitable place to integrate
it. An error message is displayed anyway.

Also again some small changes to the settings activity. Next I will
start refactoring the controller task classes.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>